In the organic EL display device, a light emission current flowing in an OLED (Organic Light Emitting Diode) as an organic EL element is controlled to adjust light emission luminance. The active matrix organic EL display device includes, within a pixel circuit, a drive transistor which controls the light emission current with a gate voltage to drive the OLED, and a transfer transistor which transfers to a gate electrode of the drive transistor a luminance voltage that is supplied from a data signal line and serves to adjust light emission luminance on multiple-gradations. The drive transistor and the transfer transistor are each formed of an insulated gate thin-film transistor (TFT).
A p-channel TFT or an n-channel TFT may be used for the drive transistor, and in the case of using the n-channel TFT, for example, there is generally given a source follower circuit where a source electrode is connected with an anode electrode of the OLED, as shown in FIG. 13 (e.g., see Patent Documents 1, 2, etc.). When the OLED is to be formed on a TFT substrate, in the case of a top emission type which emits light from its upper side, a lower electrode made up of a laminate structure of a reflective metal and a transparent electrode (formed by laminating a transparent electrode on a reflective metal layer) is arranged on the TFT substrate for a micro cavity effect, and in the case of a bottom emission type which emits light from its lower side, with the lower electrode needing to allow light emitted from the light emitting element to pass therethrough, a lower electrode made up of a transparent electrode is arranged on the TFT substrate. However, with a work function of the transparent electrode being large, the transparent electrode is desirably used as an anode electrode so as to realize light emission of the OLED in a stable and highly efficient manner. Therefore, when the drive transistor is the n-channel TFT, a source electrode is connected with the anode electrode arranged on the TFT substrate side. On the other hand, in order to avoid the source follower circuit being given, a cathode electrode using an alkaline metal with a small work function is to be arranged on the TFT substrate in place of the transparent electrode. In this case, there occurs a need for forming the cathode electrode into an extremely thin film, thereby making it difficult to form an organic film of good quality on the cathode electrode and also causing a problem of increasing resistance of the cathode electrode.